<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div {
            display: flex;
            text-align: center;
        }
    </style>
</head>

<body>
    <div class="list">

    </div>
    <button class="pre">上一页</button>
    <button class="next">下一页</button>
    <span></span>
</body>

</html>
<script>

    var page = 1;//保存当前页码

    //将对象格式转为查询字符串格式
    function objToSearchString(obj) {
        var str = '';
        //将对象obj的每个属性名和属性值拼接为 key=value& 的格式
        for (var key in obj) {
            str += `${key}=${obj[key]}&`
        }
        //返回拼接好的字符串,去除尾部的&（不去除不影响功能）
        return str.slice(0, str.length - 1);
    }

    function ajax(method, url, params, cb) {
        //1.创建请求对象
        var xhr = new XMLHttpRequest();

        //2.配置请求对象
        xhr.open(method, url + "?" + objToSearchString(params));

        //3.设置回调函数
        xhr.onreadystatechange = function () {
            if (xhr.readyState == 4) {
                cb(JSON.parse(xhr.responseText));
            }
        }

        //4.发送请求
        xhr.send();
    }
    //-------------------------------------------------------------------
    //点击上一页, 获取上一页的表情,渲染表情
    document.querySelector('.pre').onclick = function () {
       
        if (page > 1) {
            ajax('get', `https://yantianfeng.com/api/emotion`, { page: --page, count: 10 }, function (data) {
                   //渲染当前是第几页
                document.querySelector('span').innerHTML = `${page}/4`
                var str = data.emotions.map((item, index) => {
                    return `<div> <img src="${item.url}" /> <div> ${item.title} </div> </div>`
                }).join('')
                //渲染表情
                document.querySelector('.list').innerHTML = str;
                if (page == 4) { document.querySelector('.pre').disabled = true }
            });
        }
    }

    //点击下一页, 获取下一页的表情,渲染表情
    document.querySelector('.next').onclick = function () {
      
        if (page < 4) {
            ajax('get', `https://yantianfeng.com/api/emotion`, { page: ++page, count: 10 }, function (data) {
                //渲染当前是第几页
                document.querySelector('span').innerHTML = `${page}/4`
                var str = data.emotions.map((item, index) => {
                    return `<div> <img src="${item.url}" /> <div> ${item.title} </div> </div>`
                }).join('')
                //渲染表情
                document.querySelector('.list').innerHTML = str;
                if (page == 1) { document.querySelector('.next').disabled = true }
            });
        }
    }


</script>